1. Field of the Invention
Many large structures and related facilities which are built require the use of large size pipe. While joining such pipes axially by welding is not particularly difficult, it is sometimes necessary for such pipes to intersect other pipes, of the same or larger size, at an angle, in most cases from about 30.degree. to 90.degree., and to be joined by welding. Offshore towers for oil and gas exploration and production are quite often made of large size pipe with pipe used for the legs and braces, both lateral and otherwise angled, between the legs. The ends of the pipe braces are contoured or profiled to fit very closely against the surface of the legs and other surfaces to facilitate fabrication of a strong economical welded joint. Unless the properly beveled pipe brace end fits close to the leg, or some other surface to which it is to be joined, an excessive deposit of weld metal will be needed to complete the joint, thus increasing costs and fabrication time and, more importantly, the needed weld quality cannot be obtained.
It is not possible to standardize on an intersecting pipe end profile or contour because the intersected or trunk pipe and the intersecting or branch pipe for different structures can vary in diameter and thickness, and the angle of intersection can also vary. These variables inherently change the intersecting pipe end profile. A further factor is involved because the intersecting or branch pipe wall thickness affects the bevel desired for welding the joint.
2. Description of the Prior Art
Pipe Beveling Machine Co., Inc., Tulsa, Okla., offers commercially an intersectional pipe cutting apparatus represented as related to U.S. Pat. No. 3,409,282. The apparatus of the patent rotates on a ring gear around a pipe to be cut. The torch also rotates about the pipe and cuts a contour corresponding with a template edge which surrounds the pipe. The torch cuts the pipe wall laterally or at a fixed bevel. This apparatus lacks flexibility because of the fixed bevel obtained and because separate ring gears are needed for each narrow range of pipe diameters and because a separate metal template is required for each different intersecting contour.
Vernon Tool Company, Alhambra, Calif., has U.S. Pat. Nos. 3,430,938 and 3,614,077 on pipe cutting and handling apparatus. U.S. Pat. No. 3,430,938 discloses a geometric mechanism for torch cutting a contour on a rotating pipe. As the pipe rotates, a cam synchronized therewith drives an adjustable crank which moves a cutting torch support axially of the pipe to cut the contour. Such apparatus requires adjustment of the crank with change in pipe diameter and/or angle of intersection to obtain the desired pipe and contour. Also, variable pipe wall bevels are not producible with the apparatus.